Field
The present disclosure relates to an apparatus and method for determining the flow rate of a gas or liquid (e.g. any fluid) through an orifice. Certain embodiments relate to a sensor for determining flow rate through a fixed orifice positioned within a conduit or other flow path. Other embodiments could be applied to variable orifice devices. In one embodiment, the flow sensor is situated in the inhalation and exhalation circuit of a ventilator used in the breathing therapy of a patient.
Description of the Related Art
In current flow sensors, a resistance or obstruction is placed in the flow path in order to create a pressure differential. This pressure differential, or pressure drop, is used to calculate flow rate through the orifice placed in the flow path. However, it is currently believed that a high degree of resistance or obstruction is necessary in order to maximize the pressure drop in the flow path, thereby providing greater accuracy in the flow rate measurement.
As merely one example, in a respiratory measurement system, a flow sensor is placed in the air pathway of a respiratory device or ventilator used to assist a patient with breathing. However, the resistance generated by the flow sensor, and the resulting increase in pressure, increases the work or effort that the patient must exert in order to breath.